Corrosion Control and Treatment Flashcards

Which type of corrosion is most commonly found between mating surfaces of dissimilar metals?

Answer: Galvanic corrosion

Galvanic corrosion occurs when two dissimilar metals are in electrical contact in the presence of an electrolyte, causing the less noble metal to corrode.

What is the primary purpose of alodine (chromate conversion coating) treatment on aluminum?

Answer: To provide corrosion protection and improve paint adhesion

Alodine (MIL-DTL-5541) creates a chemically bonded chromate layer on aluminum that resists corrosion and serves as an excellent primer bonding surface.

Intergranular corrosion in aluminum alloys is most dangerous because it:

Answer: Attacks along grain boundaries beneath the surface with little external evidence

Intergranular corrosion progresses along grain boundaries beneath the metal surface, making it difficult to detect visually until significant structural damage has occurred.

When removing corrosion from an aluminum aircraft structure, which abrasive should NOT be used?

Answer: Steel wool or steel wire brushes

Steel wool or steel wire brushes embed steel particles into the aluminum surface, creating galvanic corrosion sites that accelerate future corrosion.

What does the term 'anodic' mean in the context of the galvanic series?

Answer: The metal is less noble and will corrode preferentially

Anodic metals are less noble (more active) in the galvanic series and will corrode preferentially when coupled with a more cathodic (noble) metal.

Which corrosion type produces a white or gray powdery deposit on aluminum surfaces?

Answer: Uniform surface corrosion (oxidation)

Uniform surface corrosion on aluminum produces aluminum oxide, which appears as a white or gray powdery or chalky deposit on the metal surface.

Before applying a corrosion-inhibiting compound (CIC) to an aircraft structure, the technician must ensure the surface is:

Answer: Clean, dry, and free of active corrosion products

CICs must be applied to clean, dry surfaces free of active corrosion; moisture or corrosion products prevent proper adhesion and reduce effectiveness.